The GAL is only populated from the user's in LDAP, so the provisioned users. If you have an external LDAP dir setup then the GAL will include those users. If you just want to load some contacts and share them with all users (and your running 4.0 RC1) then you can create a new contacts folder and share it with your team.

Looking for new beta users -> Co-Founder of Acompli. Previously worked at Zimbra (and Yahoo! & VMware) since 2005.